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Do MH, Lee HHL, Lee JE, Park M, Oh MJ, Lee HB, Park JH, Jhun H, Kim JH, Kang CH, Park HY. Gellan gum prevents non-alcoholic fatty liver disease by modulating the gut microbiota and metabolites. Food Chem 2022; 400:134038. [DOI: 10.1016/j.foodchem.2022.134038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 08/02/2022] [Accepted: 08/24/2022] [Indexed: 10/15/2022]
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2
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Onomura D, Satoh S, Ueda Y, Dansako H, Kato N. Identification of ribavirin-responsive cis-elements for GPAM suppression in the GPAM genome. Biochem Biophys Res Commun 2020; 533:148-154. [PMID: 32933750 DOI: 10.1016/j.bbrc.2020.08.112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 08/31/2020] [Indexed: 11/15/2022]
Abstract
Glycerol-3-phosphate acyltransferase, mitochondrial (GPAM) is a rate-limiting enzyme catalyzing triglyceride synthesis. Recently, we demonstrated that the anti-viral drug ribavirin (RBV) reduces GPAM expression by downregulating CCAAT/enhancer-binding protein α (C/EBPα). However, the precise mechanisms of GPAM suppression have remained unclear. Here, we found that RBV suppressed GPAM expression by downregulating not only C/EBPα, but also sterol regulatory element-binding protein-1c (SREBP-1c). We also found that cis-elements regulated by C/EBPα and SREBP-1c functioned as distal and proximal enhancers, respectively, to express hepatocyte- and adipocytes-specific GPAM variants. These results imply that RBV disrupts formation of the enhancer machineries on the GPAM genome by downregulating both transcription factors. Our findings may contribute to the development of treatments for fatty liver diseases caused by aberrant triglyceride synthesis.
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Affiliation(s)
- Daichi Onomura
- Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama, 700-8558, Japan
| | - Shinya Satoh
- Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama, 700-8558, Japan.
| | - Youki Ueda
- Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama, 700-8558, Japan
| | - Hiromichi Dansako
- Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama, 700-8558, Japan
| | - Nobuyuki Kato
- Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama, 700-8558, Japan
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Bai J, He Z, Li Y, Jiang X, Yu H, Tan Q. Mono-2-ethylhexyl phthalate induces the expression of genes involved in fatty acid synthesis in HepG2 cells. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2019; 69:104-111. [PMID: 31004931 DOI: 10.1016/j.etap.2019.04.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 03/28/2019] [Accepted: 04/08/2019] [Indexed: 06/09/2023]
Abstract
Mono-2-ethylhexyl phthalate (MEHP) is a major bioactive metabolite in the widely used industrial plasticizer diethylhexyl phthalate (DEHP) that has been found to be toxic to the liver. The aim of this study is to determine whether MEHP exposure can change the expression of fatty acid metabolism-related genes in HepG2 cells, which might be related to non-alcoholic fatty liver disease (NAFLD). The results revealed that exposure to MEHP promoted lipid accumulation in HepG2 cells. The levels of intracellular triglycerides in the hepatocytes increased after exposure to 0.8-100 μM MEHP for 24 h and 48 h. The genetic expressions of SREBP-1c, ChREBP, ACC1, FASN, and SCD significantly increased at 6 h after exposure to MEHP. At 24 h, the expression of the SREBP-1c and ChREBP genes remained increased, while the expression of the FASN and SCD genes decreased. At 48 h, the expression of SREBP-1c, ChREBP, ACC1, FASN, and SCD decreased. Furthermore, the levels of proteins including ACC1, FASN, SCD, and ChREBP (except SREBP-1c) increased at 24 h. These findings suggest that MEHP exposure can promote fatty acid synthesis in hepatocytes by regulating the expression of relevant genes and proteins, contributing to NAFLD.
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Affiliation(s)
- Jianying Bai
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan, 030001, China.
| | - Zhen He
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan, 030001, China
| | - Yaofu Li
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan, 030001, China
| | - Xuexia Jiang
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan, 030001, China
| | - Hongmei Yu
- Department of Health Statistics, School of Public Health, Shanxi Medical University, Taiyuan, 030001, China
| | - Qing Tan
- Department of Environmental Health, School of Public Health, Shanxi Medical University, Taiyuan, 030001, China
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Transcriptional Regulation of Acyl-CoA:Glycerol- sn-3-Phosphate Acyltransferases. Int J Mol Sci 2019; 20:ijms20040964. [PMID: 30813330 PMCID: PMC6412627 DOI: 10.3390/ijms20040964] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 02/14/2019] [Accepted: 02/15/2019] [Indexed: 12/13/2022] Open
Abstract
Acyl-CoA:glycerol-sn-3-phosphate acyltransferase (GPAT) is an enzyme responsible for the rate-limiting step in the synthesis of glycerophospholipids and triacylglycerol (TAG). The enzymes of mammalian species are classified into four isoforms; GPAT1 and GPAT2 are localized in the mitochondrial outer membrane, whereas GPAT3 and GPAT4 are localized in the endoplasmic reticulum membrane. The activity of each enzyme expressed is associated with physiological and pathological functions. The transcriptional regulation is well known, particularly in GPAT1. GPAT1 mRNA expression is mainly regulated by the binding of the transcriptional factor SREBP-1c to the specific element (the sterol regulatory element) flanking the GPAT1 promoter. The TAG level is controlled by the insulin-induced transcriptional expression of GPAT1, which occupies most of the GPAT activity in the liver. The transcriptional regulation of the other three GPAT isoforms remains undetermined in detail. It is predicted that retinoic acid serves as a transcription factor in the GPAT2 promoter. PPARγ (peroxisome proliferator-activated receptor γ) increases the mRNA expression of GPAT3, which is associated with TAG synthesis in adipose tissues. Although GPAT has been considered to be a key enzyme in the production of TAG, unexpected functions have recently been reported, particularly in GPAT2. It is likely that GPAT2 is associated with tumorigenesis and normal spermatogenesis. In this review, the physiological and pathophysiological roles of the four GPAT isoforms are described, alongside the transcriptional regulation of these enzymes.
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Katz LS, Xu S, Ge K, Scott DK, Gershengorn MC. T3 and Glucose Coordinately Stimulate ChREBP-Mediated Ucp1 Expression in Brown Adipocytes From Male Mice. Endocrinology 2018; 159:557-569. [PMID: 29077876 PMCID: PMC5761585 DOI: 10.1210/en.2017-00579] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 10/19/2017] [Indexed: 01/10/2023]
Abstract
Increasing brown adipose tissue (BAT) activity is regarded as a potential treatment of obese, hyperglycemic patients with metabolic syndrome. Triiodothyronine (T3) is known to stimulate BAT activity by increasing mitochondrial uncoupling protein 1 (Ucp1) gene transcription, leading to increased thermogenesis and decreased body weight. Here we report our studies on the effects of T3 and glucose in two mouse models and in mouse immortalized brown preadipocytes in culture. We identified carbohydrate response element binding protein (ChREBP) as a T3 target gene in BAT by RNA sequencing and studied its effects in brown adipocytes. We found that ChREBP was upregulated by T3 in BAT in both hyperglycemic mouse models. In brown preadipocytes, T3 and glucose synergistically and dose dependently upregulated Ucp1 messenger RNA 1000-fold compared with low glucose concentrations. Additionally, we observed increased ChREBP and Ucp1 protein 11.7- and 19.9-fold, respectively, along with concomitant induction of a hypermetabolic state. Moreover, downregulation of ChREBP inhibited T3 and glucose upregulation of Ucp1 100-fold, whereas overexpression of ChREBP upregulated Ucp1 5.2-fold. We conclude that T3 and glucose signaling pathways coordinately regulate the metabolic state of BAT and suggest that ChREBP is a target for therapeutic regulation of BAT activity.
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MESH Headings
- Active Transport, Cell Nucleus
- Adipocytes, Brown/cytology
- Adipocytes, Brown/metabolism
- Adipocytes, Brown/pathology
- Adipogenesis
- Animals
- Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
- Cell Line, Transformed
- Cells, Cultured
- Diet, High-Fat/adverse effects
- Energy Metabolism
- Fatty Acid Synthase, Type I/chemistry
- Fatty Acid Synthase, Type I/genetics
- Fatty Acid Synthase, Type I/metabolism
- Gene Expression Profiling
- Gene Ontology
- Glucose Transporter Type 4/agonists
- Glucose Transporter Type 4/genetics
- Glucose Transporter Type 4/metabolism
- Hyperglycemia/etiology
- Hyperglycemia/metabolism
- Hyperglycemia/pathology
- Male
- Mice, Inbred C57BL
- Nuclear Proteins/antagonists & inhibitors
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- Obesity/etiology
- Obesity/metabolism
- Obesity/pathology
- Promoter Regions, Genetic
- RNA Interference
- Transcription Factors/antagonists & inhibitors
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Triiodothyronine/administration & dosage
- Triiodothyronine/metabolism
- Uncoupling Protein 1/agonists
- Uncoupling Protein 1/genetics
- Uncoupling Protein 1/metabolism
- Up-Regulation
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Affiliation(s)
- Liora S. Katz
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Shiliyang Xu
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Kai Ge
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Donald K. Scott
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Marvin C. Gershengorn
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
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How lipid droplets "TAG" along: Glycerolipid synthetic enzymes and lipid storage. Biochim Biophys Acta Mol Cell Biol Lipids 2017. [PMID: 28642195 DOI: 10.1016/j.bbalip.2017.06.010] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Triacylglycerols (TAG) serve as the predominant form of energy storage in mammalian cells, and TAG synthesis influences conditions such as obesity, fatty liver, and insulin resistance. In most tissues, the glycerol 3-phosphate pathway enzymes are responsible for TAG synthesis, and the regulation and function of these enzymes is therefore important for metabolic homeostasis. Here we review the sites and regulation of glycerol-3-phosphate acyltransferase (GPAT), acylglycerol-3-phosphate acyltransferase (AGPAT), lipin phosphatidic acid phosphatase (PAP), and diacylglycerol acyltransferase (DGAT) enzyme action. We highlight the critical roles that these enzymes play in human health by reviewing Mendelian disorders that result from mutation in the corresponding genes. We also summarize the valuable insights that genetically engineered mouse models have provided into the cellular and physiological roles of GPATs, AGPATs, lipins and DGATs. Finally, we comment on the status and feasibility of therapeutic approaches to metabolic disease that target enzymes of the glycerol 3-phosphate pathway. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
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Tumor-associated GM-CSF overexpression induces immunoinhibitory molecules via STAT3 in myeloid-suppressor cells infiltrating liver metastases. Cancer Gene Ther 2016; 23:188-98. [PMID: 27199222 DOI: 10.1038/cgt.2016.19] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 03/29/2016] [Indexed: 01/08/2023]
Abstract
Assumptions that liver immune cells and immunosuppressive pathways are similar to their counterparts in other spaces have led to gaps in our understanding of intrahepatic neoplasm aggressiveness. Myeloid-derived suppressor cells (MDSCs) are potent inhibitors of antitumor immunity and pose a major obstacle to solid tumor treatment. Liver MDSCs (L-MDSCs) associated with liver metastases (LM) are particularly problematic by contributing to intrahepatic immunosuppression that promotes tumor progression. L-MDSCs have been reported to expand in response to granulocyte-macrophages colony-stimulating factor (GM-CSF) and suppress antitumor immunity in LM. To extend these findings, we examined mechanisms of intrahepatic immunosuppression exploited by L-MDSCs. We found that the majority of L-MDSCs co-expressed GM-CSF receptor (GM-CSF-R), indoleamine 2,3-dioxygenase (IDO) and programmed death ligand 1 (PD-L1), while demonstrating high levels of signal transducer and activator of transcription factor 3 (STAT3) activation. GM-CSF-secreting tumor cells induced STAT3 phosphorylation in L-MDSCs in addition to expression of IDO and PD-L1. GM-CSF or GM-CSF-R blockade markedly reduced L-MDSC IDO and PD-L1 expression, implicating tumor-derived GM-CSF in supporting L-MDSC-immunoinhibitory molecule expression. Small-molecule inhibitors of Janus-activated kinase 2 (JAK2) and STAT3 also dramatically diminished IDO and PD-L1 expression in L-MDSCs. We determined that STAT3 exerts transcriptional control over L-MDSC IDO and PD-L1 expression by binding to the IDO1 and PD-L1 promoters. Our data suggest that the GM-CSF/JAK2/STAT3 axis in L-MDSCs drives immunosuppression in a model of LM and blockade of this pathway may enable rescue of intrahepatic antitumor immunity.
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González RS, Rodriguez-Cruz M, Maldonado J, Saavedra FJ. Role of maternal tissue in the synthesis of polyunsaturated fatty acids in response to a lipid-deficient diet during pregnancy and lactation in rats. Gene 2014; 549:7-23. [PMID: 25046614 DOI: 10.1016/j.gene.2014.06.057] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 06/24/2014] [Accepted: 06/25/2014] [Indexed: 10/25/2022]
Abstract
During pregnancy and lactation, metabolic adaptations involve changes in expression of desaturases and elongases (Elovl2 and Elovl5) in the mammary gland and liver for the synthesis of long-chain polyunsaturated fatty acids (LC-PUFAs) such as arachidonic acid (AA) required for fetal and postnatal growth. Adipose tissue is a pool of LC-PUFAs. The response of adipose tissue for the synthesis of these fatty acids in a lipid-deficient diet of dams is unknown. The aim of this study was to explore the role of maternal tissue in the synthesis of LC-PUFAs in rats fed a low-lipid diet during pregnancy and lactation. Fatty acid composition (indicative of enzymatic activity) and gene expression of encoding enzymes for fatty acid synthesis were measured in liver, mammary gland and adipose tissue in rats fed a low-lipid diet. Gene expression of desaturases, elongases, fatty acid synthase (Fasn) and their regulator Srebf-1c was increased in the mammary gland, liver and adipose tissue of rats fed a low-lipid diet compared with rats from the adequate-lipid diet group throughout pregnancy and lactation. Genes with the highest (P<0.05) expression in the mammary gland, liver and adipose tissue were Elovl5 (1333%), Fads2 (490%) and Fasn (6608%), respectively, in a low-lipid diet than in adequate-lipid diet. The percentage of AA in the mammary gland was similar between the low-lipid diet and adequate-lipid diet groups during the second stage of pregnancy and during lactation. The percentage of monounsaturated and saturated fatty acids was significantly (P<0.05) increased throughout pregnancy and lactation in all tissues in rats fed a low-lipid diet than in rats fed an adequate-lipid diet. Results suggest that maternal metabolic adaptations used to compensate for lipid-deficient diet during pregnancy and lactation include increased expression of genes involved in LC-PUFAs synthesis in a stage- and tissue-specific manner and elevated lipogenic activity (saturated and monounsaturated fatty acid synthesis) of maternal tissues including adipose tissue.
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Affiliation(s)
- Raúl Sánchez González
- Laboratorio de Biología Molecular, Unidad de Investigación Médica en Nutrición, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, IMSS, México City, Mexico.
| | - Maricela Rodriguez-Cruz
- Laboratorio de Biología Molecular, Unidad de Investigación Médica en Nutrición, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, IMSS, México City, Mexico.
| | - Jorge Maldonado
- Laboratorio de Biología Molecular, Unidad de Investigación Médica en Nutrición, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, IMSS, México City, Mexico.
| | - Filiberto Jasso Saavedra
- Laboratorio de Biología Molecular, Unidad de Investigación Médica en Nutrición, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, IMSS, México City, Mexico
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Abstract
The liver plays a unique, central role in regulating lipid metabolism. In addition to influencing hepatic function and disease, changes in specific pathways of fatty acid (FA) metabolism have wide-ranging effects on the metabolism of other nutrients, extra-hepatic physiology, and the development of metabolic diseases. The high prevalence of nonalcoholic fatty liver disease (NAFLD) has led to increased efforts to characterize the underlying biology of hepatic energy metabolism and FA trafficking that leads to disease development. Recent advances have uncovered novel roles of metabolic pathways and specific enzymes in generating lipids important for cellular processes such as signal transduction and transcriptional activation. These studies have also advanced our understanding of key branch points involving FA partitioning between metabolic pathways and have identified new roles for lipid droplets in these events. This review covers recent advances in our understanding of FA trafficking and its regulation. An emphasis will be placed on branch points in these pathways and how alterations in FA trafficking contribute to NAFLD and related comorbidities.
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Buchanan JW, Garmyn AJ, Hilton GG, VanOverbeke DL, Duan Q, Beitz DC, Mateescu RG. Comparison of gene expression and fatty acid profiles in concentrate and forage finished beef1. J Anim Sci 2013; 91:1-9. [DOI: 10.2527/jas.2012-5154] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- J. W. Buchanan
- Department of Animal Science, Oklahoma State University, Stillwater 74078
| | - A. J. Garmyn
- Department of Animal Science, Texas Tech University, Lubbock 79409
| | - G. G. Hilton
- Department of Animal Science, Oklahoma State University, Stillwater 74078
| | - D. L. VanOverbeke
- Department of Animal Science, Oklahoma State University, Stillwater 74078
| | - Q. Duan
- Department of Genetics, University of North Carolina, Chapel Hill 27599
| | - D. C. Beitz
- Department of Animal Science, Iowa State University, Ames 50011
| | - R. G. Mateescu
- Department of Animal Science, Oklahoma State University, Stillwater 74078
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Abstract
Cancer cell proliferation and progression require sufficient supplies of nutrients including carbon sources, nitrogen sources, and molecular oxygen. Particularly, carbon sources and molecular oxygen are critical for the generation of ATP and building blocks, and for the maintenance of intracellular redox status. However, solid tumors frequently outgrow the blood supply, resulting in nutrient insufficiency. Accordingly, cancer cell metabolism shows aberrant biochemical features that are consequences of oncogenic signaling and adaptation. Those adaptive metabolism features, including the Warburg effect and addiction to glutamine, may form the biochemical basis for resistance to chemotherapy and radiation. A better understanding of the regulatory mechanisms that link the signaling pathways to adaptive metabolic reprogramming may identify novel biomarkers for drug development. In this review, we focus on the regulation of carbon source utilization at a cellular level, emphasizing its relevance to proliferative biosynthesis in cancer cells. We summarize the essential needs of proliferating cells and the metabolic features of glucose, lipids, and glutamine, and we review the roles of transcription regulators (i.e., HIF-1, c-Myc, and p53) and two major oncogenic signaling pathways (i.e., PI3K-Akt and MAPK) in regulating the utilization of carbon sources. Finally, the effects of glucose on cell proliferation and perspective from both biochemical and cellular angles are discussed.
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Affiliation(s)
- Chengqian Yin
- Department of Biology, College of Arts and Sciences, Drexel University, Philadelphia, Pennsylvania, USA
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Benhamed F, Denechaud PD, Lemoine M, Robichon C, Moldes M, Bertrand-Michel J, Ratziu V, Serfaty L, Housset C, Capeau J, Girard J, Guillou H, Postic C. The lipogenic transcription factor ChREBP dissociates hepatic steatosis from insulin resistance in mice and humans. J Clin Invest 2012; 122:2176-94. [PMID: 22546860 DOI: 10.1172/jci41636] [Citation(s) in RCA: 290] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 02/15/2012] [Indexed: 12/12/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is associated with all features of the metabolic syndrome. Although deposition of excess triglycerides within liver cells, a hallmark of NAFLD, is associated with a loss of insulin sensitivity, it is not clear which cellular abnormality arises first. We have explored this in mice overexpressing carbohydrate responsive element-binding protein (ChREBP). On a standard diet, mice overexpressing ChREBP remained insulin sensitive, despite increased expression of genes involved in lipogenesis/fatty acid esterification and resultant hepatic steatosis (simple fatty liver). Lipidomic analysis revealed that the steatosis was associated with increased accumulation of monounsaturated fatty acids (MUFAs). In primary cultures of mouse hepatocytes, ChREBP overexpression induced expression of stearoyl-CoA desaturase 1 (Scd1), the enzyme responsible for the conversion of saturated fatty acids (SFAs) into MUFAs. SFA impairment of insulin-responsive Akt phosphorylation was therefore rescued by the elevation of Scd1 levels upon ChREBP overexpression, whereas pharmacological or shRNA-mediated reduction of Scd1 activity decreased the beneficial effect of ChREBP on Akt phosphorylation. Importantly, ChREBP-overexpressing mice fed a high-fat diet showed normal insulin levels and improved insulin signaling and glucose tolerance compared with controls, despite having greater hepatic steatosis. Finally, ChREBP expression in liver biopsies from patients with nonalcoholic steatohepatitis was increased when steatosis was greater than 50% and decreased in the presence of severe insulin resistance. Together, these results demonstrate that increased ChREBP can dissociate hepatic steatosis from insulin resistance, with beneficial effects on both glucose and lipid metabolism.
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Takeuchi H, Sata M. The relationship among brain natriuretic peptide (BNP), cholesterol and lipoprotein. HEART ASIA 2012; 4:11-5. [PMID: 27326018 PMCID: PMC4898600 DOI: 10.1136/heartasia-2011-010042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/19/2012] [Indexed: 12/14/2022]
Abstract
OBJECTIVE To study the relationship among brain natriuretic peptide (BNP), cholesterol and lipoprotein. DESIGN A retrospective, cross-sectional study. SETTING Tokushima University Hospital area. PATIENTS A retrospective study of 46 patients (nine inpatients and 37 outpatients) with angina pectoris or arrhythmias who were seen at Tokushima University Hospital Cardiovascular Division and had measurements of their BNP, fatty acid and lipid profile. The average age of patients was 57±17 years, and 39% were male subjects. MAIN OUTCOME MEASURES BNP, dihomo-γ-linolenic acid, arachidonic acid, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), apolipoproteinA1, apolipoprotein A2 (ApoA2), apolipoprotein B (ApoB), apolipoprotein C2, apolipoprotein C3, apolipoprotein E, total cholesterol (TC), triglyceride, high density lipoprotein cholesterol and low density lipoprotein cholesterol. RESULTS The baseline characteristics of the patients were shown in table 1 and the data of lipoprotein were shown in table 2. Table 3 shows the relationship among BNP, cholesterol and lipoprotein. The authors found significant negative correlation between serum levels of BNP and ApoA2 (figure 1; r=-0.458, p=0.001), serum levels of BNP and ApoB (figure 2; r=-0.328, p=0.026) and serum levels of BNP and TC (figure 3; r=-0.383, p=0.010). There is a possibility that dietary EPA and DHA may modulate cardiac mitochondrial and autonomic nervous system dysfunction via fatty-acids-PPARs-PTEN-PI3K/Akt-SREBPs system and affect serum BNP levels indirectly. CONCLUSION BNP had significant negative correlation with ApoA2, ApoB and TC. The findings suggest that increasing serum levels of ApoA2, ApoB and TC may have an effect on improving heart function. But the mechanism is presently unclear.
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Affiliation(s)
- Hidekazu Takeuchi
- Department of Cardiovascular Medicine, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
| | - Masataka Sata
- Department of Cardiovascular Medicine, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
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14
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Participation of mammary gland in long-chain polyunsaturated fatty acid synthesis during pregnancy and lactation in rats. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1811:284-93. [PMID: 21292028 DOI: 10.1016/j.bbalip.2011.01.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 01/21/2011] [Accepted: 01/22/2011] [Indexed: 11/23/2022]
Abstract
Metabolic adaptations are triggered in the maternal organism to synthesize milk with an adequate concentration of long-chain polyunsaturated fatty acids (LC-PUFAs) required to the newborn. They may be a high uptake of dietary linoleic acid and its conversion to LC-PUFAs by desaturases of fatty acids (FADS) 1 and 2 in the mammary gland (MG). It is unknown if they also occur from onset of pregnancy. The aim of this study was to explore the participation of the MG as a mechanism involved in LC-PUFAs synthesis to support their demand during pregnancy and lactation in rats. The expression of desaturases in MG was significantly (P<0.05) higher (12.3-fold for FADS1 and 41.2-fold for FADS2) during the late pregnancy and throughout lactation (31.7-fold for FADS1 and 67.1-fold higher for FADS2) than in nonpregnant rats. SREBF-1c showed a similar pattern of increase during pregnancy but remained higher only during the early lactation (11.7-fold, P<0.005). Transcript of ELOVL6 and FASN increased throughout pregnancy and lactation, respectively. ELOVL5 mRNA increased in MG only during lactation (2.8 to 5.3-fold, P<0.005). Accordingly, a higher content of LC-PUFAs was found in lactating MG than in nonpregnant rats. Results suggest that MG participates from late pregnancy and throughout lactation by expressing desaturases and elongases as a mechanism involved in LC-PUFAs synthesis, probably by SREBF-1c. Because desaturases and ELOVL5 were expressed in cultured lactocytes and such expression was downregulated by linoleic and arachidonic acid, these cells may be a useful model for understanding the regulatory mechanisms for LC-PUFAs synthesis in MG.
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